US2985539A

US2985539A - Treated red lead

Info

Publication number: US2985539A
Application number: US776676A
Authority: US
Inventors: Konig Otto
Original assignee: Nat Lead Co
Current assignee: NL Industries Inc
Priority date: 1958-11-28
Filing date: 1958-11-28
Publication date: 1961-05-23
Anticipated expiration: 1978-05-23

Description

United States Patent ()fihce Patented May 23, 1961 3- c tl m r .(C 10 9 length of time of said paint.

Although red lead is" one of the mo t p p la nd useful anti-corrosion pigments on the market, paints made An object of this invention therefore, is to provide an improved red lead pigment.

conta n and the tendency of of tetracarboxybutane, .tetracarboxyhutane. a

'In .a particularlydesirable embodiment, this invention contemplates a composition as aforesaid wherein there and a mixture of litharge and present, but there is no particular advantage in employing such an excess. Less than 15% of the lead salt of tetracarboxybutane may be present and still provide beneficial eflects.

Not only are the anti-corrosive properties of a red lead paint retained when a increasingly viscous upon I The mechanism of this suppression of the tendencies of the paint to become viscous upon standing and to settle and form a hard mass is not fully understood.

' The lead salt of tetracarboxybutane may be prepared by reacting tetracarboxybutane' the red lead pigment and then incorporating this piginitially reacting the litharge present with the tetracarboxybutane, care being taken to insure that enough PbO is also present to react with the tetracarboxybutane presformulated into a paint. present in the red lead is such,

kn w a ve ug y occur- Th s liven'n en e y y be prevented by neutralizing the excess PbO with addit o a et ac rb x bl tane or example, o in me other np n manne n rder to more fu i us ra he a re o s i en ion d th q raq icins t s m h fo owing examp s a e s nted.-

7 Example 1 The redlead used in this example was a low PbO red lead prepared by the furnace process and containing 2.98% by weight of P1 0. Two thousand grams of this lead containing 59.6 grams of PhD (0.267 mol) were suspended in two liters of distilled water and the suspension stirred vigorously by means of a mechanical stirrer. Then 31.3 grams 0.134 mol) of l,2,3,4-tetracarboxybutane in powdered :form were introduced over a five-minute interval. Agitation was continued for an additional /2 hour after which the suspension was allowed to settle Ov n ht and n fi ter n a Bi c n nnn filtered cake was washed with distilled water until the filtrate had a substantially neutral pH. The washed filter cake was then o en u an d d a 51 and oun a hammer sni Example 11 The rrsqe lu l fixam le re ea w n ha no water was used,'and the mixture was dry ground together in a ball mill until the mixture was uniform.

Example III A paint using the pigment prepared according to Example I was formulated as follows:

Percent Pigment 70.4

0 Vehicle 29.6

which is a medium length linseed oil alkyd resin and 16.34% of Sovasol #5, which is an aliphatic petroleum mineral spirits.

A control was prepared in exactly the same manner except that the pigment contained no tetracarboxybutane or lead salt of tetracarboxybutane. The 70.4% of the control pigment contained 2.98% PbO, and 97.02% of Pb O Both paints were allowed to stand for 36 days, and the consistency of both conclusion thereof. The consistency measurements were accomplished via A.S.T.M. consistency test method D-562-55. At the end of the 36 day period, the control containing no lead salt of tetracarboxybutane had a consistency of 435 grams, while the paint wherein a lead salt of textracarboxybutane was used had a consistency of 280 grams. The original consistency of the control was 330 grams, and the original consistency of the paint containing a lead salt of tetracarboxybutane was 250 grams.

Example IV A control, identical with control of prepared except that the 70.4% of pigment of 3.05% PbO, and 96.95% of Pb O A pigment was prepared according to the process of this invention, and in particular, in the manner of Exame ple I except that 3.05% of PhD was used and a correspondingly larger stoichiometric amount of tetracarboxybutane was used. The formulation of the paint was the same as in Example I.

A second pigment was prepared according to the process of this invention, and in particular, in the manner of Example 11. The pigment was prepared by dry mixing 3.05% PbO, 96.95% of Pb O and a stoichiometric amount of tetracarboxybutane was used, said stoichiometric amount based on the amount of PbO present. A paint was formulated in the manner of Example III, that is 70.4% of the pigment mixture containing the tetracarboxybutane and 29.6% of vehicle.

All the three paints were allowed to stand for 36 days. It was found that at the end of 36 days, the control had a harder cake at the bottom of the paint receptacle then either of the other two paints which contained the treated pigment, treated according to Example I and the pigment prepared according to Example II. Both of these tetracarboxybutane treated pigments exhibited a very soft settling tendency of approximately one-eighth of an inch in height.

Example III was was composed Example V A control was prepared according to Example control contained 11.3% of PhD, and 88.7% of Pb O A paint was formulated in the manner of formulation of the control of Example HI.

A pigment was prepared in the manner of Example II, except that there was present 11.3% of PhD, a stoichio metric amount of tetracarboxybutane, and the remainder was Pb O A paint was prepared using the formulation of Example III, that is 70.4% of the mixture prepared according to Example II, and 29.6% of the vehicle.

The consistency of the paints was measured at the conclusion of the 36 day period and one day after the paints were prepared. The method used was the same as in Example III, that is A.S.T.M. D-562-55 consistency test III. This paints was measured at the:

method. The initial consistency of the control was 350 grams. The final consistency of the control was 700 grams. The initial consistency of the paint prepared according to this invention was 310 grams. The final consistency of the paint prepared according to this invention was 485 grams.

As is obvious from the foregoing examples, a pigment prepared according to the process of this invention when utilized in paints shows a marked effect in suppressing the tendency of the pa'nt to become viscous upon standing and suppresses the tendency to harden into a solid mass at the bottom of the paint receptacle. The suppression of these tendencies should result in paints with a .longer shelf life, and in a more consistent, uniform, and dependable product. The process itself, is a simple one and can readily be carried out by an operator without special skill or training.

In addition, as an interesting side note to this invention, the compositions according to this invention seem to show a marked ability to eliminate the livering problem present in red lead anti-corrosion paints.

While this invention has been described in terms of certain preferred embodiments and illustrated by means of specific examples, these are illustrative only, and the invention is not to be construed as limited, except as set forth in the following claims.

I claim:

l. A pigment composition consisting essentially of red lead, and at least one additive selected from the class consisting of a lead salt of tetracarboxybutane, and a mixture of litharge and tetracarboxybutane, said additive being present in the amount of from 4.24% to about 15% by weight based on the combined weight of said red lead and said additive; said litharge and said tetracarboxybutane being present in the proportion of at least 1 mole of tetracarboxybutane per 2 moles of litharge.

2. A method of suppressing the tendency of a red lead pigment to settle in a paint vehicle, and the tendency of the paint to become increasingly viscous which comprises adding to said red lead pigment, at least one additive selected from the class consisting of a lead salt of tetracarboxybutane, and a mixture of litharge and tetracarboxybutane, said additive being; present inthe amount of from 4.24% to about 15% by weight based 'on the combined weight of said red lead and 1 said additive; said litharge and said tetracarboxybutane being present in the proportion of at least 1 mole of tetraearboxybutane per 2 moles of litharge.

3. A paint composition containing a pigment composition according to claim 1.

References Cited in the file ofthis patent UNITED STATES PATENTS 2,182,436 Johnstone Dec. 5, 1939 ,2,236,296 Minich et al Mar. 25, 1941 2,836,483 Schulz May 27, 1958 FOREIGN PATENTS j 26,322" Great Britain .Oct. 2, 1897 264,492 Great Britain Feb. 9, 1928 Australia Aug.

Claims

1. A PIGMENT COMPOSITION CONSISTING ESSENTIALLY OF RED LEAD, AND AT LEAST ONE ADDITIVE SELECTED FROM THE CLASS CONSISTING OF A LEAD SALT OF TETRACARBOXYBUTANE, AND A MIXTURE OF LITHARGE AND TETRACARBOXYBUTANE, SAID ADDITIVE BEING PRESENT IN THE AMOUNT OF FROM 4.24% TO ABOUT 15% BY WEIGHT BASED ON THE COMBINED WEIGHT OF SAID RED LEAD AND SAID ADDITIVE, SAID LITHARGE AND SAID TETRACARBOXYBUTANE BEING PRESENT IN THE PROPORTION OF AT LEAST 1 MOLE OF TETRACARBOXYBUTANE PER 2 MOLES OF LITHARGE.